block: add queue flag for SSD/non-rotational devices
We don't want to idle in AS/CFQ if the device doesn't have a seek
penalty. So add a QUEUE_FLAG_NONROT to indicate a non-rotational
device, low level drivers should set this flag upon discovery of
an SSD or similar device type.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/as-iosched.c b/block/as-iosched.c
index 80af925..4c6fafb 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -745,6 +745,12 @@
*/
static int as_can_anticipate(struct as_data *ad, struct request *rq)
{
+ /*
+ * SSD device without seek penalty, disable idling
+ */
+ if (blk_queue_nonrot(ad->q))
+ return 0;
+
if (!ad->io_context)
/*
* Last request submitted was a write